1. Field of the Invention
The present invention relates to a position information management system, and more particularly to a system for managing the position information of pedestrians.
2. Description of the Related Art
Nowadays, a car navigation system wherein a terminal is mounted in an automobile so as to display the current position of the automobile has been put into practical use and put on the market. According to the car navigation system, anybody can reach a destination without getting lost even in an area which he/she visits for the first time, because the map of his/her surroundings is displayed with the current position.
The car navigation system executes the processing of receiving radio waves from satellites so as to acquire the current position in terms of a latitude and a longitude, and reading out map information which contains the acquired latitude and longitude, from a memory device.
Such car navigation operates to navigate the driving of the automobile. There has also been developed and put on sale a system wherein a person holds or carries a terminal of a portable type, on which his/her current position and pertinent map information are displayed so as to navigate the person.
The personal navigation system also executes the processing of receiving radio waves from satellites so as to acquire the current position in terms of a latitude and a longitude, and displaying the stored map information with the current position.
The system wherein the current position is determined by receiving the radio waves from the satellites in this manner, is called the “GPS (Global Positioning System)”.
Meanwhile, in the navigation system as stated above, the current position is acquired by catching the radio waves from the satellites. Therefore, the system has the disadvantage of failing to operate in a location where the radio waves cannot be received from any of the satellites.
Besides, in the system for navigating the movements of a person, the terminal to be held or carried by the person tends to be somewhat large in size because a CD-ROM or the like for storing map information is built therein.